High operation reliability and reduced chip size are features that are demanded from semiconductor memory. In recent years, there has been an effort to improve operation reliability for semiconductor devices while reducing power consumption. As part of that effort to improve the data reliability, stable power supply in the semiconductor devices has been playing an important role.
Generally, a semiconductor device (e.g., a semiconductor chip) may provide a power supply voltage internally or may distribute an external power supply voltage. For example, the semiconductor device may include a power supply circuit and a voltage detection circuit that detects voltage drop due to in-chip circuit operation. The power supply circuit may provide the power supply voltage responsive to the voltage drop to stabilize the power supply voltage, however such response of the power supply circuit may have a delay relative to the voltage drop, and some instability in the power supply voltage due to voltage drop during the delay may remain. The instability throughout the semiconductor device (e.g., a voltage between a gate node and a source node of transistors in the semiconductor device) may cause noise on circuits on the semiconductor device. To reduce such noise, a compensation capacitance element for compensating the power supply voltage may be provided between power supply lines having a positive power supply voltage VDD and a negative power supply voltage Vss (e.g., a ground level, etc.).
For example, a compensation capacitance element including capacitors where each capacitor has a structure similar to a structure of a capacitor in a memory cell. The compensation capacitance element may have a current leakage when a voltage difference between one end and the other end of the compensation capacitance element exceeds a threshold voltage. In order to prevent the current leakage, a plurality of compensation capacitance elements coupled in series may be provided to have a voltage difference lower than the threshold voltage for each compensation capacitance element. The plurality of compensation capacitance elements may have resistance at intermediate nodes between the plurality of compensation capacitance elements. If the resistance at the intermediate nodes exceeds a threshold resistance, a current may become too weak to compensate the power supply voltage. When the capacitance to be obtained by the plurality of compensation capacitance elements is large while fitting the plurality of compensation capacitance elements in a limited space of the semiconductor device, the resistance may become too high.
For example, a wire may be inserted in parallel to the series of compensation capacitance elements to reduce the resistance at the intermediate nodes, however, the wire may occupy an extra space. Alternatively, the compensation capacitance elements may be divided, however, a manner of dividing may depend on arrangements of the capacitors in the compensation capacitance elements. Furthermore, dividing each compensation capacitance element into a plurality of compensation capacitance elements in parallel may reduce the resistance at the intermediate nodes, however, dividing into the plurality of compensation capacitance elements in parallel requires extra spaces for margins between the plurality of compensation capacitance elements.